Superpolarizing neutron coatings: Theory and first experiments

A new method for improving polarizing neutron coatings is theoretically substantiated and experimentally verified. It is based on the use of layers with a negative potential of definite thickness to suppress reflection of neutrons with the undesired spin from the potential barriers formed by structural imperfections. Estimations showed that Ti, Co or Ti/Co interlayers at the interfaces and a protective Ti/TiO2 surface bilayer may increase the flipping ratio for reflection from polarizing neutron coatings by orders of magnitude. It opens the possibility to build polarizers and analyzers of new generation. Superpolarizing coatings not only will improve the performance and thus widen the range of applications of the polarizing devices, but also may be the basis for designing novel neutron instrumentation. Even ultra-cold neutron beams can be efficiently polarized and analyzed with new polarizing neutron optics. A method for precise measurements of NSF and SF reflectivities of the spin-down neutrons for polarizing coatings with the nipping ratios up to 10(3)-10(4) is suggested (method of two samples). (C) 2009 Elsevier B.V. All rights reserved.